Methyl 5-substituted oxazole-4-carboxylates were synthesized by the reaction of methyl α-isocyanoacetate with acylating reagents in the presence of bases. The oxazole methyl esters were converted into the carboxylic acids and the carboxamides. Then, N-alkyl-oxazole-4-carboxamides were prepared through the oxazole-4-carboxylic acid chloride. Furthermore, 2-substituted oxazoles were synthesized by cyclization of N-acyl-α-benzoylglycine methyl esters. which were obtained by acylation of α-benzoylglycine methyl ester followed by ammonolysis of the resulting oxazole methyl esters. These oxazole compounds were evaluated for inhibitory activity on blood platelet aggregation in vitro and ex vivo. Some of these compounds showed the inhibitory activity comparable to that of aspirin. Of these, 5-(3, 4, 5-trimethoxyphenyl) oxazole-4-carboxamide was the most active compound in the ex vivo test.